When a table was explicitly locked with LOCK TABLES no associated
tables from any related trigger on the subject table were locked.
As a result of this the user could experience unexpected locking
behavior and statement failures similar to "failed: 1100: Table'xx'
was not locked with LOCK TABLES".

This patch fixes this problem by making sure triggers are
pre-loaded on any statement if the subject table was explicitly
locked with LOCK TABLES.